The present invention relates to a wireless network where User Equipment (UE) communicates with a radio access network (RAN).
A control plane may be used for all control signaling between the UE and the RAN. A user plane may be used to transmit and receive all user information. Common resources and dedicated resources are defined in a cell for the uplink and the downlink transmission between UEs and the RAN. For example, a Random Access Channel (RACH) and a Forward Access Channel (FACH) could represent common transport channels for the uplink and the downlink, respectively. The RACH is a contention-based uplink transport channel, where a dynamic persistence level parameter controls the rate at which a UE accesses the RACH.
A UE is said to be in IDLE mode when no connection to the RAN exists, for example, following a power-up of a UE. When a signaling connection is established, i.e. control plane connection, a UE is said to be in CONNECTED mode. Once in connected mode, both control plane signaling and user plane information can be exchanged between the UE and the RAN.
An idle mode UE requests a control plane signaling connection by transmitting a CONNECTION REQUEST message over a common channel, such as the RACH. An establishment cause may be included in the connection request message to inform the RAN of the reason why the UE is requesting the connection. The RAN can admit or reject the UE""s request for a signaling connection. In the former case, the UE can be admitted for signaling over common resources (CELL_FACH state) or signaling over dedicated resources (CELL_DCH state). A Call Admission Control (CAC) algorithm may be used to evaluate the allocation of dedicated resources for the uplink and/or downlink transmission between a UE and the RAN.
There is currently, however, no available methods for determining whether a UE should be admitted for a control plane signaling connection and, if admitted, should the UE be admitted for signaling over common resources or dedicated resources. Some current systems simply always admit UEs to common resources regardless of the common resources"" level of congestion, thereby arbitrarily increasing congestion and often causing the UE to experience significant delay in the exchange of signaling information.
A method is therefore needed to determine whether a UE should be admitted for control plane signaling and, if admitted, whether the UE should be admitted for signaling over common resources or dedicated resources.
The invention is a method for admission control of control plane signaling connection requests. The admission control method determines whether to accept or reject a UE for a control plane signaling connection. In the former case, the method determines whether the UE will be admitted for signaling over common resources or dedicated resources. In the latter case, the UE is denied access to the network and remains in its idle state.